Semiconductor devices are constructed from a semiconductor material wafer through a process that includes a number of deposition, masking, diffusion, etching, implanting, and other steps. Usually, many individual devices are constructed on the same wafer. When the devices are separated into individual rectangular units, each takes the form of an integrated circuit die or chip. In order to connect a chip with other circuitry, it is common to mount it on a metallic leadframe or multi-layer substrate. Electrical connections are made and the assemblies are completed by encapsulating them in molded resin, plastic or ceramic packages that provide protection from hostile environments and yet enable electrical interconnection between the integrated circuit chip and an outside assembly such as a printed circuit board (PCB). In general, the elements of such a package include a substrate or leadframe, an integrated circuit chip, bonding material to attach the integrated circuit chip to the leadframe, electrical connections between the integrated circuit chip and the leadframe, and a hard encapsulant material which covers the other components and forms the exterior of the package.
For purposes of high-volume, low-cost production of IC packages, one current industry practice is to prepare, usually through a process of etching and/or stamping, a thin sheet of metal to form a panel or strip which defines multiple leadframes arranged in one or more arrays or strips. Multi-chip arrays may also be formed on semiconductor wafer material. In a common chip package manufacturing process, the integrated circuit chips are mounted to respective locations on the substrates, with the encapsulant material then applied to the strip or array so as to collectively encapsulate all of the integrated circuit chips, any bond wires used to connect the chips to the substrates, and all or regions of each of the substrates. The process of manufacturing “block-molded” semiconductor packages, wherein numerous chips on a strip or array are encapsulated within a single molded body, is widespread in the art. Subsequent to the curing of the encapsulant, the substrates and their associated chips and leads are then cut apart or singulated for purposes of producing the individual chip packages. One common technique by which singulation is typically accomplished is a saw singulation process. In this process, the array of block molded devices is held down on a cutting table, using a vacuum or mechanical jig, while a saw blade is advanced through the array in prescribed patterns between the block-molded chips as required to facilitate the separation of the individual packaged chips from one another.
In saw singulation processes using adhesive tape for securing workpieces, a block-molded strip or array of devices is ordinarily placed and secured atop a cutting table and sawn into individual device packages. Typically, a block-molded array of ICs is mounted in a mounting ring using adhesive tape. A cutting table or platform is used to support the mounting ring as it holds the block-molded array. The mounting ring is in turn held in place by an arrangement typically including a frame and a holding mechanism such as a vacuum-equipped cutting table designed for that particular purpose. A spindle assembly is positioned above the secured array and is used to bring a rotating saw blade into contact with the array for cutting. An optical device such as a camera is used to align and control the path of the saw blade. Nozzles positioned near the saw blade are typically used to cool the array and saw blade during sawing and for dispensing solvent such as high pressure water or soapy water to wash away sawdust particles and waste generated by the sawing process.
Saw singulation employing adhesive tape for securing block-molded devices is widely used. However, there are significant problems remaining in the present state of the art. For example, during saw singulation, sawdust including mold compound, silicon, metal, or other particles are typically generated by the cutting action of the saw. The sawdust has a tendency to settle on nearby surfaces such as the singulated devices and the remainder of the array(s) during further cutting. Additionally, scrap pieces, particularly at the edges of the arrays, are produced during cutting. The exposed areas of adhesive tape adjacent to the array(s) provides a tacky surface to which particles and scraps tend to adhere. Efforts to wash away adhering particles and scraps are not completely effective. As a result, scraps can impede sawing and damage or break the saw blade during further cutting. Also, particles of contaminants that become stuck to the tape can later become dislodged and can be transferred to completed devices during subsequent cleaning and handling. Due to the technical challenges and problems with the present state of the art, improved systems and methods for singulating block-molded semiconductor devices would be useful and advantageous in the arts. The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems described above.